Systems and methods for efficiently moving a variety of objects

ABSTRACT

A programmable motion system is disclosed that includes a dynamic end effector system. The dynamic end effector system includes a plurality of acquisition units that are provided at an exchange station within an area accessible by the programmable motion device, and a coupling system for coupling any of the plurality of acquisition units to an end effector of the programmable motion device such that any of the acquisition units may be automatically selected from the exchange station and used by the programmable motion device without requiring any activation or actuation by the exchange station and without requiring any intervention by a human.

PRIORITY

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 62/618,184, filed Jan. 17, 2018, the disclosure ofwhich is hereby incorporated by reference in its entirety.

BACKGROUND

The invention generally relates to programmable motion systems andrelates in particular to end effectors for programmable motion devices(e.g., robotic systems) for use in object processing such as objectsortation.

End effectors for robotic systems may be employed, for example, incertain applications to select and grasp an object, and then move theacquired object very quickly to a new location. End effectors should bedesigned to quickly and easily select and grasp an object from a jumbleof dissimilar objects, and should be designed to securely grasp anobject during movement. Certain end effectors, when used on differentobjects of different physical sizes, weights and materials, may havelimitations regarding how securely they may grasp an acquired objectduring rapid movement, particularly rapid acceleration and deceleration(both angular and linear).

Many end effectors employ vacuum pressure for acquiring and securingobjects for transport and/or subsequent operations by articulated arms.Other techniques for acquiring and securing objects involveelectrostatic attraction, magnetic attraction, needles for penetratingobjects such as fabrics, fingers that squeeze an object, hooks thatengage and lift a protruding feature of an object, and collets thatexpand in an opening of an object, among other techniques. Typically,end effectors are designed as a single tool, such as for example, agripper, a welder, or a paint spray head, and the tool is typicallydesigned for a specific set of needs.

There remains a need however, for an end effector system in aprogrammable motion system that may select and grasp any of a widevariety of objects, and then move the acquired object very quickly to anew location.

SUMMARY

In accordance with an embodiment, the invention provides a programmablemotion system that includes a dynamic end effector system. The dynamicend effector system includes a plurality of acquisition units that areprovided at an exchange station within an area accessible by theprogrammable motion device, and a coupling system for coupling any ofthe plurality of acquisition units to an end effector of theprogrammable motion device such that any of the acquisition units may beautomatically selected from the exchange station and used by theprogrammable motion device without requiring any activation or actuationby the exchange station and without requiring any intervention by ahuman.

In accordance with another embodiment, the invention provides aprogrammable motion system that includes a dynamic end effector system.The dynamic end effector system includes a plurality of vacuum cupsthrough which a vacuum may be provided, and each of which may beattached to an end effector of the end effector system, wherein theprogrammable motion system is capable of accessing any of the pluralityof vacuum cups, and a coupling system for coupling any of the pluralityof vacuum cups to the end effector of the end effector system of theprogrammable motion device.

In accordance with a further embodiment, the invention provides aprogrammable motion system that includes a dynamic end effector system.The dynamic end effector system includes a plurality of acquisitionunits that are provided within access to the programmable motion deviceon an acquisition unit rack, the acquisition unit rack being movable inat least two mutually orthogonal directions.

In accordance with yet a further embodiment, the invention provides amethod of providing the processing of objects using a programmablemotion system. The method includes the steps of providing a plurality ofvacuum units, each of which may be attached to an end effector of theend effector system, and each of which may provide a vacuumtherethrough, accessing any of the plurality of vacuum units, couplingany of the plurality of vacuum units to the end effector of the endeffector system of the programmable motion device, and using the coupledvacuum unit to grasp and move an object by the programmable motiondevice.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description may be further understood with reference tothe accompanying drawings in which:

FIG. 1 shows an illustrative diagrammatic view of an object processingsystem in accordance with an embodiment of the present invention;

FIG. 2 shows an illustrative diagrammatic view of a view from aperception system of the system of FIG. 1 directed down into a bin on aconveyor;

FIG. 3 shows an illustrative diagrammatic view of a secondary perceptionsystem of the system of FIG. 1 ;

FIG. 4 shows an illustrative diagrammatic view of a programmable motiondevice of the system of FIG. 1 including articulated arm sections and anend effector section;

FIG. 5 shows an illustrative diagrammatic view of the end effectorsection of the programmable motion device of FIG. 4 ;

FIG. 6 shows an illustrative diagrammatic view of an exchange station ofthe system of FIG. 1 ;

FIG. 7 shows an illustrative diagrammatic top view of the exchangestation of FIG. 5 ;

FIG. 8 shows an illustrative diagrammatic side view of the exchangestation of FIG. 6 ;

FIGS. 9A and 9B show illustrative diagrammatic views of an end effectorand an acquisition unit uncoupled (FIG. 9A) and coupled (FIG. 9B);

FIG. 10 shows an illustrative diagrammatic top view of the exchangestation of FIG. 6 without the acquisition units;

FIG. 11 shows an illustrative diagrammatic side view of the exchangestation of FIG. 10 ;

FIGS. 12A-12D show illustrative diagrammatic views of an acquisitionunit being exchanged from an end effector to an exchange station inaccordance with an embodiment of the present invention;

FIG. 13 shows an illustrative diagrammatic view of a portion of theexchange station of FIG. 10 ;

FIG. 14 shows an illustrative diagrammatic view of an exchange stationin accordance with another embodiment of the present invention thatincludes passive retention magnets;

FIG. 15 shows an illustrative diagrammatic top view of the exchangestation of FIG. 14 ;

FIG. 16 shows an illustrative diagrammatic top view of an exchangestation in accordance with a further embodiment of the present inventionthat involves a friction fit between the brackets and the acquisitionunits;

FIG. 17 shows an illustrative diagrammatic of an acquisition unitengaged with the exchange station of FIG. 16 ;

FIG. 18 shows an illustrative diagrammatic view of a portion of anexchange station in accordance with a further embodiment of the presentinvention that further includes an acquisition unit identificationperception system;

FIG. 19 shows an illustrative diagrammatic side view of an acquisitionunit with identifying indicia engaged with the exchange station of FIG.18 ;

FIG. 20 shows an illustrative diagrammatic side view of an end effectorand an acquisition unit in accordance with a further embodiment of thepresent invention that includes an acquisition unit presence detectionsystem;

FIG. 21 shows an illustrative diagrammatic bottom view of theacquisition unit presence detection system of FIG. 20 ;

FIG. 22 shows an illustrative diagrammatic side view of the end effectorand acquisition unit of FIG. 20 coupled together;

FIG. 23 shows an illustrative diagrammatic top view of the acquisitionunit of FIG. 20 ;

FIG. 24 shows an illustrative diagrammatic side view of an end effectorand an acquisition unit in accordance with a further embodiment of thepresent invention that includes an acquisition unit identity detectionsystem;

FIG. 25 shows an illustrative diagrammatic bottom view of theacquisition unit presence detection system of FIG. 24 ;

FIG. 26 shows an illustrative diagrammatic side view of the end effectorand acquisition unit of FIG. 24 coupled together;

FIG. 27 shows an illustrative diagrammatic top view of the acquisitionunit of FIG. 24 ;

FIG. 28 shows an illustrative diagrammatic view of the exchange stationportion of FIG. 13 mounted in an x-y movement accommodation structure;

FIG. 29 shows an illustrative diagrammatic view of the exchange stationportion of FIG. 13 mounted in an x-y-z movement accommodation structure;

FIG. 30 shows an illustrative diagrammatic view of an exchange stationportion mounted in an x-y movement accommodation structure that includesan x-y position zeroing system;

FIG. 31 shows an illustrative diagrammatic view of an exchange stationportion mounted in an x-y-z movement accommodation structure thatincludes an x-y-z position zeroing system;

FIG. 32 shows an illustrative diagrammatic view of an end effectorincluding an accommodation structure in accordance with a furtherembodiment of the present invention;

FIG. 33 shows an illustrative diagrammatic side view of the end effectorof FIG. 32 ;

FIG. 34 shows an illustrative diagrammatic view of an end effector andan acquisition unit with a vacuum passing therethrough;

FIG. 35 shows an illustrative diagrammatic plan view of a processingsystem in accordance with an embodiment of the present invention; and

FIGS. 36A-36D show illustrative diagrammatic views of an acquisitionunit being coupled to an end effector (FIGS. 36A and 36B), engaging anobject (FIG. 36C), and transferring the acquisition unit to an exchangestation (FIG. 36D).

The drawings are shown for illustrative purposes only.

DETAILED DESCRIPTION

In accordance with an embodiment the invention provides a programmablemotion system for moving objects for processing, such as sortation andorder fulfillment. In applications such as order fulfillment, objectsare collected into heterogeneous sets and need to be processed intoappropriate groupings. In particular, individual objects need to beidentified (e.g., by perception systems) and then routed toobject-specific locations. The described system reliably automates thegrasping and movement of such objects by employing both a robotic armand versatile gripping systems. In accordance with various embodiments,the perception units (e.g., cameras or scanners) may look for a varietyof codes such as indicia, e.g., barcodes, radio frequency identification(RFID) tags, Stock Keeping Unit (SKU) codes, Universal Parcel Codes(UPC), low wavelength IR (LWIR), as well as invisible barcodes anddigital watermarks such as Digimarc DWCode, etc.

Sorting for order fulfillment is one application for automaticallyidentifying objects from a heterogeneous object stream. Barcode scannershave a wide variety of uses including identifying the Stock Keeping Unitof an article, or tracking parcels. The system described herein may havemany uses in the automatic identification and processing, e.g.,sortation, of objects.

Such a system automates part of the sorting process in conjunction witha robotic pick and place system, and in particular, the step of graspingand carrying objects. A robotic arm, for example, picks an object from abin, places the object in front of (or drops an object into) a scanner,and then, having obtained identification information for the object(such as a barcode, QR codes, UPC codes, other identification codes,information read from a label on the object, or assessed size, weightand/or shape information), routes the object toward the appropriate binor shelf location by either moving the object itself, or placing theobject in or on a conveyance system. Since certain scanners employcameras or lasers to scan 1D or 2D symbologies printed on labels affixedto objects, the barcodes must be visible to the scanner's sensors forsuccessful scanning in order to automatically identify items in aheterogeneous stream of arbitrary objects, as in a jumbled set ofobjects found in a bin.

Further applications for grasping systems of the invention includesortation for a wide variety of applications, including orderfulfillment, collection of objects for shipping, and collection ofobjects for inventory purposes etc. Further, such grasp planning systemsof the invention may be used for loading break-packs (organized packagesfor later breaking apart at a different location), palletization(loading pallets), de-palletization, truck loading, truck unloading etc.As used herein, the term “destination locations” involves locations atwhich objects are placed for any purpose, not necessarily a finaldestination, and not necessarily for sortation for order fulfillment.

In accordance with various embodiments, therefore, the inventionprovides a method for determining the identity of an object from acollection of objects, as well as a method for perceiving theinformation regarding an object employing one or more perception units(cameras or scanners), and a robotic arm with an end-effector forholding the object. The invention further provides a method fordetermining a sequence of placements of a robot end-effector so as tominimize the time it takes a configuration of one or more cameras orscanners to successfully scan an object, and a method for scanning theidentification information (such as a barcode, QR codes, UPC codes,other identification codes, information read from a label on the object,or assessed size, weight and/or shape information) of an object byemploying a scanner as an end-effector on a robotic arm.

An important aspect is the ability to identify identification or mailinginformation for the object (such as a barcode, QR codes, UPC codes,other identification codes, information read from a label on the object,or size, weight and/or shape information) of objects by employing aprogrammable motion device such as a robot arm, to pick up individualobjects and place them in front of one or more scanners or to drop orplace the object into a scanner. In accordance with other embodiments,the programmable motion device may include a parallel arm robot(Delta-type arm) or a linear indexing pick and place system. Certainconvention scanning systems, for example, may be unable to see labels orbarcodes on objects that are presented in a way that this information isnot exposed or visible.

Important components of an automated processing system in accordancewith an embodiment of the present invention are shown in FIG. 1 . FIG. 1shows a programmable motion system 10 that includes an articulated arm12 that includes an end effector 14 and articulated sections 16, 18 and20. The articulated arm 12 selects objects from an input area such as aconveyor 22 that are either in a bin on the conveyor 22, or are on theconveyor itself. A stand 24 includes an attached perception unit 26 thatis directed toward the conveyor from above the conveyor 22. Theperception unit 26 may include, for example, a 2D or 3D camera, or ascanner such as a laser reflectivity scanner or other type of bar-codereader, or a radio frequency identification (RFID) scanner. Theperception unit 26 is positioned to acquire perception data regardingobjects that are provided on a conveyor 22 or in a bin that is on theconveyor 22. Based on the perception data, the system 10 determines oneor more grasp locations on an object, and directs the end effector 14 onthe articulated arm 12 to grasp the object.

Images taken by the perception unit 26 may be displayed on a touch inputscreen 28 so that persons in the environment may interact with thesystem 10, e.g., by confirming, rejecting or proposing, possible grasplocations on objects, based on which the system 10 may undergo machinelearning (e.g., in processor 34) with regard to the objects. FIG. 2 ,for example, shows objects 40, 42, 44, 46, 48, 50, 52, 54 in a bin 56 onthe conveyor 22. Associated with each object are possible grasplocations and orientations that the gripper may use to grasp theobjects. While certain grasp locations 58 are good, others, such as 60are not good grasp locations for a variety of reasons, such as forexample, that the object is presently blocked by other objects. Eitherwith or without prompts, a human may enter information through theinteractive touch input screen regarding which grasp locations proposedby the system 10 are good, which grasp locations proposed by the system10 are bad, and/or which grasp locations not proposed by the system 10would be advised.

The system 10 provides that when an object has been grasped by the endeffector 14 of the articulated arm 12, the end effector 14 may presentthe object to a perception station 29. As further shown in FIG. 3 , theperception station 29 includes a plurality of light sources 31 (e.g.,LEDs, or fluorescent, phosphorescent or incandescent lights), as well asa plurality of perception units 33 (e.g., scanners or cameras) forreading barcodes, radio frequency identification (RFID) tags, StockKeeping Unit (SKU) codes, Universal Parcel Codes (UPC), low wavelengthIR (LWIR) information or invisible barcodes and digital watermarks.While the perception unit 26 may have detected any such label or codeupon grasp planning if the label or code was facing the perception unit26, the additional perception units 33 at the perception station 29provide views of all remaining sides of the object when the end effector14 positions the object within the perception station 29.

Having identified a code or indicia, the processing system 34 then pullsrouting information regarding the object, and the articulated arm 12then moves the object using the end effector 14 to an appropriatelocation 32 of a bank of sortation locations 30. The end effector 14further includes an acquisition unit 72 (such as a vacuum unit, e.g., avacuum cup) for contacting and grasping the objects. In an embodiment,the acquisition unit 72 may be in the form of a flexible bellows, andmay include a vacuum line 80 attached to the end effector 14 forproviding a vacuum source at the mouth of the flexible bellows.

As further shown in FIG. 4 , the acquisition unit 72 is coupled to aconduit 84, the other end of which 82 is coupled to the vacuum line 80(shown in FIG. 1 ). The conduit 84 is adapted to linearly slide into andout of an end effector base 85 in relatively small amounts. The endeffector 14 provides the vacuum through the conduit to the acquisitionunit 72. The end effector 14 is attached to the articulated arm via acoupling mechanism 90 that includes clamp arms 92. A slidable anchor 94is attached to the conduit 84 such that as the conduit 84 slides in andout of the end effector base 85, the anchor moves along a track 96. Whenthe anchor 94 (and the conduit 84) moves toward the base 85, the upperspring 87 is compressed, and then the anchor 94 moves away from the base85, the lower spring 89 is compressed. The end effector 14 therebypermits the end acquisition unit 72 to move toward and away from thebase 85 against the forces of springs in either direction to accommodateaxial forces that are applied to the acquisition unit 72 during use. Thecoupling mechanism 90 includes an attachment plate 95 for coupling tothe robotic arm. In further embodiments, the coupling mechanism may alsoinclude a low profile load plate (e.g., a load cell or a torque forcesensor system) for monitoring load forces on the acquisition unit 72.

With reference to FIG. 6 , the system may further provide a plurality ofacquisition units (e.g., 74, 76) in addition to unit 72 that are suitedfor grasping different objects. In certain embodiments, the acquisitionunits are vacuum cups that provide passage of a vacuum therethrough. Asan example, the different acquisition units 72, 74, 76 may each be adifferent size, and be suited for grasping different objects havingdifferently sized flat areas (for grasping). As further shown withreference to FIGS. 7 and 8 , a rack 78 on which the additionalacquisition units 74, 76 are provided, may include sets of opposingbrackets 77, 79, between which a rim 100 on each acquisition unit may bepositioned. When each acquisition unit 74, 76 is held by the rack 78, anundersurface 102 of a rim 100 rests against a lower bracket of therespective pair of brackets 77, 79.

In accordance with certain embodiments, therefore, the inventionprovides a programmable motion system including a dynamic end effectorsystem. The dynamic end effector system includes a plurality ofacquisition units and coupling means. The plurality of acquisition unitsare provided at an exchange station within an area accessible by theprogrammable motion device. The coupling means is for coupling any ofthe plurality of acquisition units to an end effector of theprogrammable motion device such that any of the acquisition units may beautomatically selected from the exchange station and used by theprogrammable motion device without requiring any activation or actuationby the exchange station and without requiring any intervention by ahuman. While a human may place a new actuation unit onto the rack, andmay then inform the system as to which actuation unit is placed on therack and where it is placed, this is not required. The system mayoriginally be set up such that the system is programmed to know whichactuation units began in which positions (and thereafter track anymovement via exchanges). In other embodiments, the vacuum cups may haveunique physical or magnetic features that may be detected by the endeffector.

The exchange station (such as the rack 78) is therefore inactive in thatthe system does not require the exchange station to actively open orclose any latches, or move any carousels, etc. The programmable motionsystem knows where the rack is positioned, and knows and monitors whichactuation units (e.g., vacuum cups) are on the rack and where each ispositioned. The programmable motion system may therefore process theobjects while switching vacuum cups automatically depending on inputfrom the perception unit(s) 26 and/or 29.

When an acquisition unit (e.g., 72) is returned to the rack 78, the unitis moved in a direction as generally shown at A in FIG. 6 such that therim 100 moves freely between the lower 77 and upper 79 brackets of areceiving station. Once the rim 100 is between the brackets 77, 79, theend effector 14 is moved upward (as shown at B in FIG. 8 ). The conduit84 includes a collar 105 having a plurality of magnets 106 (of similarpolarity orientation), and the magnetic field provided by the magnets106 retains the metal end 108 of the acquisition unit around a mountingpost 110 (as further shown in FIG. 9A). When the end effector 14 ismoved upward (again, as shown at B in FIG. 8 ), the upper-side 104 ofthe rim 100 is stopped against the upper 79 of the pair of brackets, andthe magnetic force causing the end 108 of the acquisition unit 72 toremain attached to the post 110, is overcome. The end effector thenmoves away from the acquisition unit 72, leaving the acquisition unitsuspended from the underside 102 of the rim 100.

With reference again to FIGS. 9A and 9B, the end effector 14 may thenattach a new acquisition unit to the end effector by lowering the end ofthe conduit 84 with the magnets 106 into an open ferromagnetic end 108of the acquisition unit to secure the acquisition unit to the mountingpost 110 at the end of the conduit 84. The end effector is then moved ina direction opposite that shown at A in FIG. 6 to move the acquisitionunit away from the rack 78 so that it may be used in processing objectsas discussed above. In accordance with various embodiments, the magnetsmay be provided on either or both elements, and either unit may befitted over the other element. FIGS. 10 and 11 further show top and sideviews of the rack 78 including the pairs of brackets 77, 79. The system10 therefore, permits that articulated arm may select differentacquisition units depending on a variety of factors such as the objectsbeing presented to the perception unit 26.

The interaction of the brackets 77, 79 and the rim 100 is further shownin FIGS. 12A-12D, which show the acquisition unit 72 being returned tothe rack. In particular, the acquisition unit 72 is moved (again in thedirection as shown at A in FIG. 6 ) onto the rack such that the rim 100is positioned between the brackets 77, 79. The end effector is thenlifted in the direction as shown at B in FIGS. 12B and 12C, and theupper-side 104 of the rim 100 contacts and is stopped by the undersideof the upper bracket 79. The force of movement of the end effector indirection B is then caused to exceed the retention force created betweenthe magnets 106 and the ferromagnetic end 108 of the acquisition unit72. The conduit 84 is thereby separated from the acquisition unit 72 (asshown in FIG. 12C), and the acquisition unit 72 then drops slightly suchthat the underside 102 of the rim 100 is held by the lower bracket 77(FIG. 12D).

FIG. 13 shows a view of a portion of the brackets 78 including the lower(77) and upper (79) brackets. The curved shape 81 is designed to matchthe circular shape of the acquisition units 72, 74, 76, and the openingdistance (d_(l)) between the brackets 77 and 79 is designed to easilyaccommodate the rim 100 of an acquisition unit 72, 74, 76.

FIG. 14 shows a system in accordance with a further embodiment of thepresent invention similar to that shown in FIG. 6 , where like referencenumerals indicate similar components. The system provides a plurality ofacquisition units (e.g., 74, 76) in addition to unit 72 (that is showncoupled to the end effector 14) that are suited for grasping differentobjects. In certain embodiments, the acquisition units are vacuum cupsthat provide passage of a vacuum therethrough. The system of FIG. 14further includes magnets 75 on the bracket 78, and the magnets 75 are inclose contact with the top rim 101 of the acquisition units (72, 74, 76)when an acquisition unit is engaged on the bracket 78. Since the top rim101 of the acquisition units are ferromagnetic, the magnets 75 act aspassive retention systems that keep the acquisition units (72, 74, 76)from sliding or vibrating off of the rack 78. FIG. 15 shows a plan viewof the rack 78 with the magnets 75, and shows the top rim 101 of theacquisition units 74, 76 fitting over the magnet 75 when engaged withthe rack 78.

FIGS. 16 and 17 show a further passive retention system that acts tomaintain the acquisition units on the rack 78. The diameter (d₂) of thearced opening in each bracket 77, 79 is designed to be the same as orwithin 0.5% of the diameter (d₃) (e.g., d₂ may be 0.5% smaller than d₃)of the neck section 103 of each acquisition unit. In accordance withfurther embodiments, the inner surface 105 of the brackets 77, 79 may becoated with a resilient material such as rubber. The rubber allows asame size diameter or even larger sized diameter acquisition unit to befirmly held by the rack 78 since the rubber compresses and firmlyengages the metal neck of the acquisition unit.

In accordance with a further embodiment and with reference to FIGS. 18and 19 , the rack 78 may further include a detection unit 88 thatincludes one or more perception systems 83 (e.g., cameras or scanners),that detect identifying indicia 107 on the neck section 103 of eachacquisition unit. The identifying indicia may be different for eachacquisition unit, and the system may thereby confirm the identity andlocation of each acquisition unit on the rack.

FIGS. 20-23 show an end effector with an acquisition unit presencedetection system. In particular, the end effector 14 includes adetection unit 91 (e.g., a photo-detection unit) that includes on abottom surface 93 thereof, a detector 97 (e.g., a camera, photo-opticdetector or magnetic detector) that detects the presence (or absence) ofa top surface 98 of the acquisition unit. FIG. 20 shows a side view ofthe detection unit and FIG. 21 shows a bottom view of the detection unitas it faces the acquisition unit. FIG. 22 shows the acquisition unitcoupled to the end effector, and FIG. 23 shows a top view of theacquisition unit, with the top surface 98 as well as the bellows portion99 and the opening portion 115 of the end effector. The system maythereby confirm that an acquisition unit is either coupled to the endeffector, or has been successfully returned to the rack and is no longeron the end effector.

FIGS. 24-27 show an end effector with an acquisition unit identitydetection system. In particular, the end effector 14 includes anidentity detection unit 123 that includes on a bottom surface 125thereof, one or more detectors 127 (e.g., cameras or a scanners) thatdetects the identifying indicia 135 of a top surface 129 of theacquisition unit. FIG. 24 shows a side view of the identity detectionunit and FIG. 25 shows a bottom view of the identity detection unit asit faces the acquisition unit. FIG. 26 shows the acquisition unitcoupled to the end effector, and FIG. 27 shows a top view of theacquisition unit, with the top surface 129 and identifying indicia 135as well as the bellows portion 99 and the opening portion 115 of the endeffector. The system may thereby confirm the identity of an acquisitionunit is coupled to the end effector.

Further flexibility may be built into systems of the invention byproviding that the bracket rack 78 may be mounted to a frame 110 thatincludes a first beam 112 that extends in a first direction along therack 78, and is coupled to the rack by spring elements 114 as shown inFIG. 28 . The frame 11 also includes a second beam 116 that extends inan orthogonal second direction, and is coupled to the rack by springelements 118. The spring elements 114, 118 provide that the rack 78 maymove in two mutually orthogonal directions (x and y as shown) bypermitting the spring elements to flex, and by providing that the springelements may pivot about mounting posts 120. In particular, when springelements 114 are flexed, the mount 120 on spring element 118 will permitspring elements 118 to pivot, accommodating the movement in the xdirection. When spring elements 118 are flexed, the mount 120 on springelement 114 will permit spring elements 114 to pivot, accommodating themovement in they direction. While only a portion of the frame 110 andthe rack 78 are shown, it will be understood that at least two springelements 118 are used (on either end of the rack), and any number of twoor more spring elements 114 should be used. Movement in the x directionmay be limited by hard stops 113 on at least either end of the rack (onesuch x direction hard stop is shown). Movement in the y direction may belimited by hard stops 117 on at least either end of the rack (one such ydirection hard stop is shown).

FIG. 29 shows an embodiment of the present invention that is similar tothat shown in FIG. 28 and discussed above, wherein the frame 110 iscoupled to at least two anchors 122 (only one is shown), and the anchors122 slide along a vertical member 124 within springs 126, 128. Thevertical member 124 is captured between braces 130, 132, and themovement of the springs 130, 132 provides that the frame 110 may bemoved in a third (z) direction as shown. The spring elements 114, 118function as discussed above, and the loose fitting of the anchor 122around the vertical member 124 permits these elements to accommodatemovement of the frame (and rack) in the x and y directions. When theframe 110 (and the rack 78) move upward, spring 126 is compressed, andwhen the frame 110 moves downward, spring 128 is compressed. Again,movement in the x direction may be limited by hard stops 113 on at leasteither end of the rack (one such x direction hard stop is shown), andmovement in they direction may be limited by hard stops 117 on at leasteither end of the rack (one such y direction hard stop is shown).Movement in the z direction may be limited by hard stops provided by theunderside of 131 of brace 130, and by the upper-side 133 of brace 132.In alternate embodiments, the movement in the z direction mayeffectively be limited by providing a relatively high spring constant ofthe springs 126 and 128 on at least either end of the rack (one such xdirection hard stop is shown). Again, two such z direction movementsystems may be provided on either end of the rack 78.

The systems of FIGS. 28 and 29 therefore provide that when a roboticsystem is positioning a retention device (e.g., a vacuum cup) eitheronto the rack or seeking to remove a retention device from the rack(changing a cup), small misalignments between the end effector and therack (in x and y directions in FIG. 28 , and in x, y and z directions inFIG. 29 ), will be accommodated without damaging the rack. Theaccommodation may be provided by both the rack and/or the end effectoras discussed above. Such movements do have stop limits to protectagainst damage.

FIG. 30 shows a system similar to the system of FIG. 28 where likereference numerals refer to the same components, and further wherein thesystem includes both an x-position zeroing system and a y-positionzeroing system. The x-position zeroing system may include a spring orother biasing system, or a selectively actuated electromagnet 109 that,when activated, draws the magnetic rack toward the electromagnet 109 asshown in FIG. 30 . Similarly, the y-position zeroing system may includea spring or other biasing system, or a selectively actuatedelectromagnet 111 that, when activated, draws the magnetic rack towardthe electromagnet 111 as shown in FIG. 30 .

FIG. 31 shows a system similar to the system of FIG. 29 where likereference numerals refer to the same components, and further wherein thesystem includes an x-position zeroing system, a y-position zeroingsystem and a z-position zeroing system. The x-position zeroing systemand the y-position zeroing system as discussed above with reference toFIG. 30 , and the z-position zeroing system may include a spring orother biasing system, or a selectively actuated electromagnet 119 that,when activated, draws either the second beam 116 (if ferromagnetic) or aferromagnetic element 121 within the second beam 116, toward theelectromagnet 119 as shown in FIG. 31 .

The x-y position zeroing system of FIG. 30 , and the x-y-z positionzeroing system of FIG. 31 may be used at times when the programmablemotion (e.g., robotic) system needs or would benefit from having therack 78 in a specific (not floating) position, for example, whenacquiring an acquisition unit from the rack 78.

FIGS. 32 and 33 show an end effector 140 in accordance with a furtherembodiment of the invention that may be used interchangeably with theacquisition units 72, 74, 76 discussed above to provide accommodation ofthe end effector. The acquisition unit 142 includes a rim 144 forengaging brackets on a rack as discussed above, and the end effectorincludes a set of retention magnets 146 on a distal end of a conduit148. The system also includes springs 150 152 that permit the conduit148 to undergo spring biased linear movement with respect to an endeffector base 154. The end effector 140 also includes a low profile loadcell or force torque sensor 160 mounted on a load cell or force torquesensor bracket 158. The low profile load cell or force torque sensor iselectrically coupled to the processing system 34, and provides dataregarding forces that are undergone by the acquisition unit whileattached to the end effector. The portion 156 that couples to a vacuumline, is also mechanically isolated from the conduit 148 by beingattached to a vacuum plate that is coupled to the non-end-effector sideof the load cell or force torque sensor, where the end effector iscoupled to the articulated arm. The use of this arrangement and thevacuum plate 162 provides that any strains or forces from the vacuumline (as with either robotic arm is moved or as the vacuum line may bemoved or not permitted to move), such strains or forces will not betransmitted to the acquisition device nor to the low profile load cellor force torque sensor.

Systems of certain embodiments of the present invention provide that anacquisition unit, such as a vacuum cup (e.g., a flexible bellows typevacuum cup), through which a high vacuum may be designed to flow, may beexchanged for another vacuum cup during use, by the programmable vacuumdevice. In particular, and with reference to FIG. 34 , a high flowvacuum may be provided to flow through an acquisition unit 200 from abase 210 up through an opening 208. When coupled to an end effector thatincludes a coupling unit 202 (having magnets 204), a collar 206 and aconduit of the end effector 212, the high flow vacuum is maintainedthrough the end effector, and in particular, through the interior 214 ofthe conduit 212. Again, the coupling unit 202 couples the end effector212 to the acquisition unit by having the magnetic field created by themagnets 204 pull the ferromagnetic top portion 216 of the acquisitionunit 200 toward the coupling unit 204, such that the collar 206 of theend effector is engaged within the interior of the acquisition unit 200when the acquisition unit 200 is engaged with the end effector 212. Bothbefore and after coupling, a high flow vacuum (V_(h)) is permitted toflow through the units as shown.

FIG. 35 shows a diagrammatic view of a system 250 in accordance with anembodiment of the present invention. The system 250 includes aprogrammable motion device 252 (such as a robotic unit) that includes anend effector 254 for grasping and moving objects. The end effector 254on the programmable motion device 252 may have a reach as far as an arcas generally shown at 256. Within this reach 256, the end effector 254of the programmable motion device 252 may reach destination bins 260(such as shown at 30 in FIG. 1 ), may reach perception station 282, mayreach the conveyor 258 (such as shown at 22 in FIG. 1 ) and destinationbins 260, and may reach a vacuum cup changer station 262 including a cupchanger rack 278 that includes vacuum cups 272, 274, 276. The system mayalso include a touch input screen 280 as discussed above (with referenceto touch input screen 28 in FIG. 1 ). The system further provides thatthe programmable motion device may identify an object in the bin 260(using the perception unit 268 or by moving the object to the perceptionstation 282), select an appropriate acquisition device from the cupchanger rack 278, acquire the selected acquisition device from the cupchanger rack 278, and then grasp the identified object in the bin 260for movement to the destination bins 260. The system therefore providesthat the programmable motion device may not only access the objects tobe processed and the destination bins, but may also access a vacuum cupchanger station at which vacuum cups may be changed during processingbased on object identification information detected by the perceptionunit 26, 268 or the perception unit 29, 282.

If an object is identified by the perception unit 282 that requires adifferent vacuum cup than is currently attached to the end effector, theend effector may place the object back into the bin so that the objectmay be again grasped, but by a newly attached acquisition device. Incertain embodiments, the perception unit 268 may sufficiently identify anext object, and if the vacuum cup on the end effector needs to bechanged, the system may exchange a current vacuum cup to a desired onethat is known to be a better acquisition unit for grasping theidentified object in bin 260.

The system may further seek to identify all objects in a bin 260, mayassociate each with an optimal vacuum cup, and may then seek to grasp,one at a time, each of the objects associated with a common vacuum cupprior to changing the vacuum cup on the end effector. In each of theseembodiments, the system itself identifies the need to change acquisitionunits, and then changes acquisition units by itself in the normal courseof operation.

Systems of certain embodiments of the invention may also employ machinelearning to improve performance over time. The system provides theperformance of picking as a function of item, pick station and handlingparameters. Further, objects that have not yet been picked willperiodically be encountered. It is likely, however, that new objectsthat are similar to previously picked items, will have similarperformance characteristics. For example, object S may be a kind ofshampoo in a twenty ounce bottle, and object C may be conditioner in atwenty ounce bottle. If distributed by the same company, then the shapeof the bottles may be the same. Systems of embodiments of the inventioninclude processes that use observations of past performance on similaritems to predict future performance, and learn what characteristics ofthe items available to the system are reliable predictors of futureperformance.

In accordance with certain embodiments, the system provides a learningprocess that (a) extrapolates the performance of newly seen objects, and(b) is continually updating the data with which it learns to extrapolateso as to continually improve performance. The potential pick parametersare diverse. Several controllable pick parameters may govern theprocess, such as, which picking stations can pick a given item, whicheffectors (vacuum cup size or gripper type) are effective for that item,and what rules might be used to choose locations on an item to graspetc. Because these process parameters can change on a per-SKU basis, andwill determine the efficacy and speed of a picking station and furthermay be determined on a per-SKU basis, it is necessary to estimate theseparameters correctly. In particular, the correct values of processparameters depend on the nature of the item, its weight and size, itspackaging, its material properties such as whether it is deformable orclear, whether vacuum grippers are effective at holding it, where goodgrasp locations are on the object, and whether it is easily damaged.

In many operating conditions however, this can be challenging, as newSKUs may be present, which means that for a new object, there is noknown set of parameters available. While these parameters will belearned from repeated interactions with the object, this can slow downhandling time considerably. To speed up the time it takes to learn theappropriate parameters, using previously recorded data based on similarSKUs can be useful.

In accordance with various embodiments, the invention provides processesfor an automated material handling system that routes bins to pickingstations, and which provides the following. The system may predictobject-specific parameters for new objects based on previously seenobjects. For new objects similar to previously handled objects, theprocesses predict what are expected to be good routing and handlingparameters. In this instance an object is readily recognized as beingquite similar to objects with which the system has extensive experience.From the bar code or SKU number or product category or description textor from appearance or other features, the system might recognize theobject and index information in the database, which might includeprocess parameters, or will at least include information from whichprocess parameters can be determined with high confidence.

Further, the system may explore the parameter space for completelyunknown objects. For new objects that are not sufficiently similar toany previously handled objects, the system may propose multiplecandidate routing and handling parameters with the aim of finding goodrouting and handling parameters. When an unfamiliar object is firstintroduced, process parameters must be determined.

The system may also update predictive models of object-specific handlingperformance from observed item handling performance. Processes refinethe routing and handling parameters on an object basis, as experiencewith that object is gained. The predictive model is refined asexperience is gained.

The system may further update predictive models of object-to-objectsimilarity from observed object handling performance. The parametersaffecting the schemes and processes for classifying and/or clusteringobjects are refined as experience with all available items is increased.Further, the system may recognize and correct for persistentdiscrepancies in actual versus predicted performance. Some objects, whenreplenished by the manufacturer, have different weights, packaging orother characteristics that impact the object's handling performance. Oldrouting and handling parameters that yielded good performance before maybe inappropriate for the changed object. When the actual performancerepeatedly exceeds the range of the predicted performance, the systemfavors exploration of the parameter space.

The coupling of the different vacuum cups to an end effector via themagnets also presents fewer limitations on the lifting dynamics. Inparticular, and with reference to FIGS. 36A-36D, the coupling unit 204attached to the conduit 212 is drawn toward the ferromagnetic top 208 ofthe vacuum cup 272 by a magnetic field Fm as shown in FIG. 36A. Becausethe object when lifted does not hang from the vacuum cup (but rather isdrawn by the vacuum V_(h)), the strength of the magnetic field is lessof a factor in the grasping and lifting. In particular, and withreference to FIGS. 36B and 36C, the object is lifted by the force of thevacuum (e.g., a high flow vacuum) V_(h), which as discussed above, flowsthrough both the vacuum cup 272 and the conduit 212. It is the vacuumV_(h) that is used to grasp an object 290 as shown in FIG. 36C. Althoughthe grasping is not reliant on the magnetic field F_(m), the strength ofthe magnetic field F_(m) may become a factor if the weight of the object290 (or its effective movement force due to acceleration) is closelymatched to the lifting force created by the vacuum force of V_(h), tolift the object 290. This is due to atmospheric pressure both beingapplied to the object and being applied to the vacuum cup (and inparticular to any radially outwardly extending flanges) while a vacuumexists within the cup. Adjusting the strength of the magnetic field mayminimize this. Adjusting the shape of the vacuum cup may also helpminimize this, for example, by providing for parallel walled cups orcups that include radially inwardly sloping walls toward the objectengagement surface.

In accordance with further embodiments of the invention, it may bedesirable to design the vacuum cup such that any seal between the cupand an object will become compromised in the event that too large aweight is attempted to be lifted (protecting the magnetic coupling frombeing breached or protecting the articulated arm from overload). Suchvacuum cups may, for example, permit some portions of the cup to open orotherwise break the seal between the cup and the object, therebyreleasing the object from the vacuum cup.

Upon returning a vacuum cup 272 to a rack 278, the vacuum cup is placedon the rack as discussed above, and the coupling unit 204 and conduit212 are pulled upward away from the rack. The rim 300 of the vacuum cup272 is stopped by the underside of the upper bracket 279 as discussedabove, and the vacuum cup 272 is separated from the coupling unit 204and conduit 212 when the reactive force of the rack F_(r) overcomes themagnetic force f_(m) as shown in FIG. 36D.

Those skilled in the art will appreciate that numerous modifications andvariations may be made to the above disclosed embodiments withoutdeparting from the spirit and scope of the present invention.

What is claimed is:
 1. A programmable motion system comprising: aprogrammable motion device that includes a robotic arm having an endeffector; an exchange station comprising a rack that provides access toa plurality of acquisition units within an area accessible by theprogrammable motion device and a frame to which the rack is mounted; andcoupling means for coupling any of the plurality of acquisition units tothe end effector of the programmable motion device such that any of theacquisition units is capable of being automatically selected from theexchange station and used by the programmable motion device withoutrequiring any activation or actuation by the exchange station andwithout requiring any intervention by a human, wherein the rack of theexchange station comprises shaped portions for holding the plurality ofacquisition units and a plurality of magnets positioned on the shapedportions of the rack for engaging a ferromagnetic portion of one or moreof the plurality of acquisition units, wherein the rack is mounted tothe frame by a plurality of spring elements such that the rack is ableto move in two mutually orthogonal directions, wherein the frame ismovably coupled to a vertical member such that the rack is configured tomove in a third direction that is mutually orthogonal to the twomutually orthogonal directions, and wherein the frame includes aposition zeroing system comprising a plurality of electromagnets thatare selectively activated to draw the rack towards a bias position inany of the three mutually orthogonal directions.
 2. The programmablemotion system as claimed in claim 1, wherein at least one of saidacquisition units includes a flexible bellows.
 3. The programmablemotion system as claimed in claim 1, wherein said end effector includesa conduit for coupling a vacuum source to a distal end of the endeffector, wherein said acquisition unit provides a vacuum at a distalend thereof, and wherein the conduit is linearly slidable with respectto an end effector base that is coupled to the robotic arm.
 4. Theprogrammable motion system as claimed in claim 1, wherein said couplingmeans includes at least one coupling magnet.
 5. The programmable motionsystem as claimed in claim 1, wherein each of said acquisition unitsincludes a retention member for engaging a retention surface of the rackto aid in a removal of any of said acquisition units from the endeffector.
 6. The programmable motion system as claimed in claim 5,wherein the retention member includes an annular shoulder.
 7. Theprogrammable motion system as claimed in claim 5, wherein said retentionsurface of the rack includes at least one wall that engages theretention member as the retention member is moved past the at least onewall.
 8. The programmable motion system as claimed in claim 7, whereinsaid at least one wall is provided by a first bracket of a pair ofbrackets.
 9. The programmable motion system as claimed in claim 8,wherein a second bracket of the pair of brackets prevents a respectiveacquisition unit from falling from the rack.
 10. The programmable motionsystem as claimed in claim 1, wherein the rack is spring biased to aframe for movement in at least two mutually orthogonal directions. 11.The programmable motion system as claimed in claim 1, wherein the rackis spring biased to a frame for movement in three mutually orthogonaldirections.
 12. A programmable motion system comprising: a robotic armhaving an end effector; an acquisition unit rack that provides access toa plurality of acquisition units within an area accessible by therobotic arm and a frame to which the rack is mounted; a plurality ofvacuum cups through which a vacuum is providable being held on theacquisition unit rack, each vacuum cup being capable of attaching to theend effector of the robotic arm, the end effector of the robotic armbeing capable of accessing any of the plurality of vacuum cups; andcoupling means for coupling any of the plurality of vacuum cups to theend effector of the robotic arm, wherein the end effector of the roboticarm comprises an identity detection unit positioned on a distal endthereof, the identity detection unit comprising at least one camera orscanner configured to detect identifying indicia provided on a topsurface of an acquisition unit prior to coupling the acquisition unit tothe end effector, and wherein the rack is mounted to the frame by aplurality of spring elements such that the rack is able to move in twomutually orthogonal directions, wherein the frame is movably coupled toa vertical member such that the rack is configured to move in a thirddirection that is mutually orthogonal to the two mutually orthogonaldirections, and wherein the frame includes a position zeroing systemcomprising a plurality of electromagnets that are selectively activatedto draw the rack towards a bias position in any of the three mutuallyorthogonal directions.
 13. The programmable motion system as claimed inclaim 12, wherein at least one of said vacuum cups includes a flexiblebellows.
 14. The programmable motion system as claimed in claim 12,wherein said end effector includes a conduit for coupling a vacuumsource to a distal end of the end effector, wherein the conduit islinearly slidable with respect to an end effector base that is coupledto the robotic arm.
 15. The programmable motion system as claimed inclaim 12, wherein said coupling means includes at least one couplingmagnet.
 16. The programmable motion system as claimed in claim 12,wherein each of said vacuum cups includes a retention member forengaging a retention surface of the acquisition unit rack to aid in aremoval of any of said vacuum cups from the end effector.
 17. Theprogrammable motion system as claimed in claim 16, wherein the retentionmember includes an annular shoulder.
 18. The programmable motion systemas claimed in claim 16, wherein said retention surface of the rackincludes at least one wall that engages the retention member as theretention member is moved past the at least one wall.
 19. Theprogrammable motion system as claimed in claim 12, wherein said at leastone wall is provided by a first bracket of a pair of brackets.
 20. Theprogrammable motion system as claimed in claim 12, wherein a secondbracket of the pair of brackets prevents a respective vacuum cup fromfalling from the rack.
 21. The programmable motion system as claimed inclaim 12, wherein the rack is spring biased to a frame for movement inat least two mutually orthogonal directions.
 22. The programmable motionsystem as claimed in claim 12, wherein the rack is spring biased to aframe for movement in three mutually orthogonal directions.
 23. Aprogrammable motion system comprising: an acquisition unit rack thatprovides access to a plurality of acquisition units that are providedwithin access to a robotic arm having an end effector, wherein theacquisition unit rack comprises shaped portions for holding theplurality of acquisition units; and a frame to which the acquisitionunit rack is mounted, wherein the acquisition unit rack is mounted tothe frame by a plurality of spring elements such that the acquisitionunit rack is able to move in two mutually orthogonal directions, whereinthe frame is movably coupled to a vertical member such that theacquisition unit rack is configured to move in a third direction that ismutually orthogonal to the two mutually orthogonal directions, andwherein the frame includes a position zeroing system comprising aplurality of electromagnets that are selectively activated to draw theacquisition unit rack towards a bias position in any of the mutuallyorthogonal directions.
 24. The programmable motion system as claimed inclaim 23, wherein the acquisition unit rack is spring-biased to a framefor movement in at least two mutually orthogonal directions.
 25. Theprogrammable motion system as claimed in claim 23, wherein theacquisition unit rack is spring-biased to a frame for movement in threemutually orthogonal directions.
 26. A method of providing the processingof objects, said method comprising: providing a plurality of vacuum cupson an acquisition unit rack, each vacuum cup capable of being attachedto an end effector of a robotic arm; identifying a vacuum cup among theplurality of vacuum cups provided on the acquisition unit rack using anidentity detection unit positioned at a distal end of the end effector,the identity detection unit comprising at least one camera or scannerconfigured to detect identifying indicia provided on a top surface ofthe vacuum cup; coupling the vacuum cup to the end effector of therobotic arm, wherein the vacuum cup is identified using the identitydetection unit prior to coupling the vacuum cup to the end effector; andapplying a vacuum through the coupled vacuum cup to grasp and move anobject by the robotic arm, wherein the rack is mounted to the frame by aplurality of spring elements such that the rack is able to move in twomutually orthogonal directions, wherein the frame is movably coupled toa vertical member such that the rack is configured to move in a thirddirection that is mutually orthogonal to the two mutually orthogonaldirections, and wherein the frame includes a position zeroing systemcomprising a plurality of electromagnets that are selectively activatedto draw the rack towards a bias position in any of the three mutuallyorthogonal directions.
 27. The method as claimed in claim 26, wherein atleast one of said vacuum cups includes a flexible bellows.
 28. Themethod as claimed in claim 26, wherein said end effector includes aconduit for coupling a vacuum source to a distal end of the endeffector, wherein the conduit is linearly slidable with respect to anend effector base that is coupled to the robotic arm.
 29. The method asclaimed in claim 26, wherein said coupling involves use of at least onecoupling magnet.
 30. The method as claimed in claim 26, wherein each ofsaid vacuum cups includes a retention member for engaging a retentionsurface of the acquisition unit rack to aid in a removal of any of saidvacuum cups from the end effector.
 31. The method as claimed in claim30, wherein the retention member includes an annular shoulder.
 32. Themethod as claimed in claim 30, wherein said retention surface of theacquisition unit rack includes at least one wall that engages theretention member as the retention member is moved past the at least onewall.
 33. The method as claimed in claim 32, wherein said at least onewall is provided by a first bracket of a pair of brackets.
 34. Themethod as claimed in claim 33, wherein a second bracket of the pair ofbrackets prevents a respective vacuum cup from falling from theacquisition unit rack.
 35. The method as claimed in claim 26, whereinthe acquisition unit rack is spring biased to a frame for movement in atleast two mutually orthogonal directions.
 36. The method as claimed inclaim 26, wherein the acquisition unit rack is spring biased to a framefor movement in three mutually orthogonal directions.
 37. The method asclaimed in claim 35, wherein the acquisition unit rack is selectivelymoved to a zero position.
 38. The programmable motion system as claimedin claim 1, wherein the end effector of the robotic arm comprises anidentity detection unit positioned on a distal end thereof, the identitydetection unit comprising at least one camera or scanner configured todetect identifying indicia provided on a top surface of an acquisitionunit prior to coupling the acquisition unit to the end effector.
 39. Theprogrammable motion system as claimed in claim 12, wherein theacquisition unit rack further comprises a plurality of detection unitspositioned on the rack, each detection unit including any of a camera ora scanner that detects identifying indicia provided on a portion of eachacquisition unit held on the rack.
 40. The programmable motion system asclaimed in claim 12, wherein the acquisition unit rack comprises shapedportions for holding the plurality of acquisition units, and theacquisition unit rack further comprising a plurality of magnetspositioned on the shaped portions of the acquisition unit rack forengaging a ferromagnetic portion of an acquisition unit.
 41. The methodas claimed in claim 26, further comprising: identifying each vacuum cupheld on the rack using a plurality of detection units positioned on therack, each detection unit including any of a camera or a scanner fordetecting identifying indicia provided on a portion of each vacuum cup.42. The method as claimed in claim 26, wherein the acquisition unit rackcomprises shaped portions for holding the plurality of vacuum cups, andwherein the method further comprises: engaging a ferromagnetic portionof a vacuum cup held of the acquisition unit rack using a plurality ofmagnets positioned on the shaped portions of the rack.
 43. Theprogrammable motion system as claimed in claim 12, wherein theacquisition unit rack is mounted to the frame by a plurality of springelements such that the acquisition unit rack is able to move in twomutually orthogonal directions, and wherein the frame is movably coupledto a vertical member such that the acquisition unit rack is configuredto move in a third direction that is mutually orthogonal to the twomutually orthogonal directions.
 44. The programmable motion system asrecited in claim 43, further comprising a position zeroing systemincluding a plurality of electromagnets that are selectively activatedto draw the acquisition unit rack towards a bias position in any of thethree mutually orthogonal directions.